Tuesday, 13 January 2015

The Atoms of Democritus

And Newton’s Particles of Light
Are Sands upon the Dead Sea Shore
Where Israel’s Tents do Shine so Bright.

I’m not quite sure what Bill Blake meant by that. I think he meant that Democritus, in faffing about wondering whether there was an absolute limit to how small you can cut things up, and Newton, in wondering if light might be a stream of tiny particles, were somehow not noticing how wonderful and astonishing is the world and everything in it. It’s a criticism that is still often made of science, and it’s a mistaken criticism: all science proceeds from wonder, and tends ad majorem Dei gloriam, or, if you object to ‘Dei’ — if you think the word ‘God’ lacks a referent — then substitute ‘Nature’ or whatever.

We would now — speaking too loosely — say that Democritus was ‘right’. That it is ‘in fact’ impossible to cut something — say, a piece of iron — into pieces below a certain size. (I’m not talking of course about the difficulty of making a knife hard and sharp enough, or of our clumsiness in using it — I’m assuming limitless sharpness and dexterity; talking ‘theory’ not ‘practice’.) Hence Democritus’s word ‘Atom’, from Greek ‘A-tomo’; ‘uncuttable’.

The mediæval alchemists took this idea a step further, getting even closer to the ‘truth’: they said that perhaps after all you could cut even a single atom of iron into smaller pieces, but whereas a single atom of iron is still iron, still has the usual iron-ish properties, were you to cut it up further you would get things that weren’t iron-ish any more; the things we call electrons and protons. Which we now ‘know’ is ‘in fact’ the case. (An analogy, though I fear not a very good one, might be cutting up a cake, and finding that eventually one finishes up with tiny bits of butter, sugar, flour etc.; the stuff of which cakes are made, but not yet cake.) (Incidentally it’s interesting that in present day Greek the word ‘Atomo’ means a person; if you cut a person into little bits he isn’t a person any more.)

Why the plethora of inverted commas? Because it’s going too far ever to say that that’s what things are ‘really’ like. Modern theory of atoms, protons, electrons etc. and how and why they behave as they ‘do’ is still only theory; just as much theory as Democritus’s brilliant idea. True, it’s a jolly good theory as theories go; that’s to say, it’s been around a while, it has a lot of explanatory value, and to date nothing too serious has turned up, in spite of diligent searching, to prove it nonsense.

But it is nonsense, or very nearly so: scientific theories are never more than plausible pictures or analogies; they never ‘become fact’.

It may come as a shock to non-scientists, but all decent scientists would agree:


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